Winter Squash are from the Americas, and Cucurbita Moschata varieties are known to have been cultivated in Southern Mexico and Peru for some 7500 years by the native peoples. Cucurbita Maxima varieties were originally native to South America, while Cucurbita Pepo varieties were native to North America. The word “Squash” comes from the native word “askutasquash”, which means “the green thing to be eaten raw”. though we prefer them cooked!! The varieties derived from Cucurbita Maxima or Cucurbita Pepo, are much easier to grow as they are quicker to mature and have a diverse range of sizes, colours and shapes.
Cucurbita Maxima varieties can be identified by their swollen and corky fruit stalks, when the fruit are ripe.
Cucurbita Pepo varieties can be identified by their ridged cylinder fruit stalks, that do not become corky when the fruit ripen.
Cucurbita Moschata varieties can be identified by their five-angled, knobbly fruiting stalk, which does not become corky.
They are called Winter Squashes, as while they grow over the Summer and Autumn, most varieties will store for three or four months, and some will even store for a year, over the winter, in a cool dry place.
For culinary use, it is best to grow the smaller varieties as they have been developed to have the sweeter, nuttier taste, rather than the Pumpkin type. Avoid the ornamental type of squash or gourds, as they can have a poor taste.
Winter Squash are greedy feeders and benefit from a rich soil including plenty of well rotted manure or compost. They must have plenty of water to keep growing vigorously.
Sow the seeds edge on, pointed end down, in heat in individual cells early in April or May, and acclimatise in a frost free place such as a cool greenhouse or cold frame. Plant out when all danger of frost is over in early June. In the North of the UK, it is a good idea to provide cloche protection for the first month, as there are frequently strong, cold East winds.
Warning. On no account plant out these sub-tropical plants before the last expected date for frost in your area. This could be mid May for the mildest areas such as Southern coastal areas, and early June in the North of the UK. Even then, provide cloche or fleece protection for the first few weeks as cold nights and winds will cause plant damage. Gardeners are regularly caught out by late frosts occurring during the traditional cold period known as “The Ice Saints”, usually just before mid May. Remember, one night of a late frost will kill your sub-tropical plants!!
Allow a spacing of about 1 square m per plant. As they can have very large trailing vines for several metres, grow them in large beds and allow the trailing vines to trail past each other. It is possible to stop them running amok like triffids, by pinching out the growing tips after several fruits have set and started growing. If you are very short of space, it is possible to let them grow up a trellis, but you will probably need to support the individual fruits with individual nets, as the fruits are so heavy.
Protect them from slugs and snails, and strong winds just after planting out. When they start to flower, provide access to the bees to carry out pollination.
Hand pollination of the flowers may be required If growing in a poly-tunnel or greenhouse, or if there are few bees about. This is done by transferring pollen from the male flower to the female flower, as shown in the photo to the right. Normally, this is only effective where the male and female flowers are from plants of the same species. Eg. Both plants could be from cucurbita maxima species but may be different varieties.
Once the fruit form, keep the fruits off the ground as shown to the left, with a slate or tile, to prevent rot. Also pinch off and remove the faded and wizened remains of the flower to prevent rot starting in wet weather.
Leave the fruit to mature and harden off into October. Winter squash only develop their full sweetness and taste when allowed to mature and harden off, according to a breeder of Winter Squash. When the foliage has died down, cut off the fruits leaving if possible, at least 5 cm stem attached, to help to prevent early rotting of the fruit. Leave the cut fruits to fully dry off in a sunny dry place, such as a greenhouse, cold frame or sunny windowsill for two weeks.
Storage of Winter Squash is best in a cool, dry and frost free place. Do not store alongside apples or pears, as the ethylene gas given off by them can cause the squash to start to rot. Remember to check your stored squash every week and cook any that are showing signs of rot. While in storage, the grey, green or blue skin colour can fade to allow an orange colour to shine through.
If you happen to be growing different varieties of Squash close together, they are likely to interbreed to produce an intermediate type of fruit. This will become apparent if you save the seed to plant the following year, when you are likely to get hybrid fruit.
See here for the basic method of cooking Winter Squash. Try using for Pumpkin pie, for making fruit stuffed pumpkin, for making savoury stuffed pumpkin, for making pumpkin scones, for making pumpkin soup.
There are many different varieties of Winter Squash in cultivation. For growing in the North of the UK, it is best to choose quick maturing types, such as Cucurbita Maxima or Cucurbita Pepo, in view of the cooler and shorter Summers. Those varieties with a claimed time of under 100 days from transplanting to harvest, are the most likely to be successful in the North of the UK in an average Summer.
Most varieties are of the trailing vine type and can trail for 2 to 5 m, depending on the variety. Therefore plenty of space is required. There are a few bush varieties that will only trail for 1 m in any direction.
Suggested varieties of Culinary Winter Squash
After my extensive trials of different varieties, they can be grouped to take account of ease of growing mature fruit, sweetness and taste.
Suggested sweetest, most full flavoured, long storage and quickest maturing varieties (<100 days from transplanting to harvest)
Bonbon F1. Cucurbita Maxima, buttercup type. This one came top in a recent independent taste test with a dry, sweet, nutty taste. Each fruit weighs up to 2 kg, has a good quantity of deep orange flesh and should store well into the Winter. Trailing vine up to 2 or 3 m. Brix(sweetness) up to 16 degrees and dry matter up to 20%.
Crown Prince F1. Cucurbita Maxima. This is very sweet and tasty, having large blue/grey fruits each up to 4 kg, with a good quantity of orange flesh and should store well into spring or early Summer. Trailing vine up to 3 or 4 m.
Festival F1. Cucurbita Pepo. This is a quick maturing variety that carries several, sweet tasting, small, pretty squashes. Each one is the right size for a family meal, some 1 kg, and could also be readily stuffed and then micro-waved. It is very good for storing and will regularly store into the next Summer. Trailing vine up to 2m.
Red Kuri or Uchiki Kuri. Cucurbita Maxima. Onion shaped squash. There is some dispute in the seed catalogues as to whether these are different names for the same variety or two different cultivars of the same variety. Red Kuri may be a redder cultivar. In any event, they are quick maturing with medium sweetness, a good flavour, moist flesh, weighing up to 1.3 kg each. Should store till late Winter. Trailing vine up to 3m.
Sweet Lightning. Cucurbita Pepo. Small, very sweet fruits weigh up to 0.5 Kg. Brix up to 16 degrees. Dry flesh. Stores till the Spring. Semi-bush up to 1m
Medium Sweetness and taste, with long storage and variety maturity under 120 days
Cornell Bush Delicata. Cucurbita Pepo. Produces oblong fruits about 20 cm long, with dry flesh, medium sweetness and good depth of flavour, weighing up to 0.5 Kg. Superb aroma while cooking. Stores into the Winter. Bush type up to 1.5 m across.
Blue Ballet Cucurbita Maxima. Produces Blue/Grey skinned, pear shaped fruits with orange flesh up to 1 Kg. Large seed cavity with dry, medium sweet, full flavoured, orange flesh. Stores well into the Spring. Semi-bush up to 2m.
Fairy F1. Cucurbita Moscata. Produces attractive green and golden mottled, striped fruits, which when ripe, loose the green colouring. The fruits have a small seed cavity with medium sweet, moist, flesh up to 1.5Kg weight. Trailing vine up to 4 m.
Pink Banana Cucurbita Maxima. The fruits eventually mature to a cylindrical shape of salmon pink colour, up to 3 Kg in weight. The fruits have a dry, medium sweet yellow flesh and will store into the Spring. Trailing vine up to 4 m.
“Spaghetti” Type Winter Squash, Curcurbita Pepo
This oblong squash is quick maturing and very easy to grow and has a slightly sweet yellow or orange flesh. When cooked, the flesh starts to separate from the thin skin. It can then be scraped with a fork to separate the flesh into strands of vegetable “spaghetti”. If properly hardened off like other Winter Squash, it will store into the Spring.
Suggested varieties of Spaghetti Squash.
Hasta la Pasta. F1 Very colourful variety with slightly sweet, yellow orange flesh and skin. Very quick maturing, with several oblong, up to 20 cm long fruits weighing up to 1 Kg. Trailing up to 2 m.
Pumpkin is the usual name given to the larger varieties of Winter Squash, which are usually grown to be used as lanterns at Halloween, or to be grown to win their class at village fairs or agricultural shows. This practice of using pumpkins for lamps was started by the Irish immigrants to America, instead of using a hollowed out Swede at Halloween, as was traditional in the UK. Make sure that you have transferred all your Winter Squashes to a secure place well before Halloween to avoid theft and vandalism!
While the flesh of Pumpkins is edible, it is not as flavoursome as that of the culinary types.
Suggested varieties of Pumpkin type of Squash.
Mars F1. A suitable size for Halloween carving, up to 2.5 Kg. The fruits are green skinned but turn a rich orange red when ready to harvest. 120 days to maturity. Semi-bush type.
Baby Bear. Early maturing, with small orange fruits up to 1 Kg.
Atlantic Giant. The World size record holder at 250 Kg+ and 3 m circumference!
Pests and diseases on Winter Squash
Slugs and snails can cause a lot of damage to the main stem, particularly immediately after you have planted out the young plants. Apply slug pellets immediately after planting out.
Red spider mite can hide on the underside of the leaves, and cause so much damage that the leaves start to wilt in the sun, even though the plant is well watered. Regularly check the underside of the leaves and spray as necessary.
Powdery Mildew can also be a problem in late Summer or Autumn, when you may see a white flour-like covering to the leaves. If it occurs, it will probably be late in the season, when the butternuts are hardening off, and it can probably be ignored. If you need to keep the plants growing for as long as possible, you can use a fungicide.
Wind damage. Obviously not a disease but it can cause physical damage through which other rots can start. It usually shows itself as a longitudinal crack up to 5 cm long through the main stem, caused by the wind catching the large leaves and twisting the stem backwards and forwards. It is easy for the young plants to become “leggy” while they are in a greenhouse or cold frame before planting out in their final position. Take great care while handling the plants at this stage to minimise this damage. Once planted out, peg the stems with a cane or better still, grow under cloches for the first month.
Another type of Winter Squash is the Butternut Squash. While Winter Squash are fairly easy to grow outside, even in Scotland, Butternut squash can be very difficult, as they require a much longer growing period and higher temperatures. Even with the latest breeding, they will need protection in the North of the UK to get the Butternuts to fruit and then have time to mature and harden off. While they grow well in Southern England, it would be easier to stick with Cucurbita Maxima or Cucurbita Pepo varieties of Winter Squash elsewhere further North, unless you can provide protection.
There are several ornamental types of squash available, some of which are edible such as Turk’s Turban, and others that are not worth eating.